In many applications, it is necessary to rapidly select particular items from a large number of other items, and to generate data which specifies the selected item. This data may be for input to a data-processing system, for example. If this item selection is to be performed by an operator, then an excessive amount of time may be required, if conventional methods of item selection are utilized. One method which has been used in the prior art to facilitate item selection has been to provide an item list in the form of a book, with pages bound together. Each page is perforated with an array of apertures, with an item appearing beside each aperture. To select a particular item, the page on which the item should appear is first looked up. This page is then placed over a device having a set of small push-buttons, each corresponding in position to an aperture on the page, and protruding through the page. The operator can then generate data such as an electrical signal to designate a selected item by actuating the push-button which is adjacent to that item.
The above method has the disadvantage that the push-buttons must necessarily be rather small, so that it is difficult for the operator to actuate them. In addition, the wiring arrangement among the buttons becomes rather complex.
Another method which has been adopted has been to employ an array of photoelectric elements rather than push-buttons, with each photoelectric element being positioned to correspond to one of the apertures in a page. The operator can then designate a selected item by touching a light pen to the aperture which is adjacent to that item, to generate an electrical signal from the corresponding photoelectric element. However, such use of a light pen is rather troublesome and time-consuming.
Touch-sensitive electrode plates, rather than push-buttons, have also been employed to generate signals designating particular items. However, such electrode plates have the disadvantage that a positive indication is not given to the operator when an item designating signal is generated. In the case of a push-button or key actuated switch, the movement of the bush-button or key when actuated provides a positive indication to the operator that actuation has been accomplished.